KR20160118817A - Catalyst for fuel cell, method of preparing the same, and membrane-electrode assembly for fuel cell including the same - Google Patents

Abstract

Provided is a catalyst for fuel cells, including a reaction inducing material including oxide represented by chemical formula 1, Ir_aRu_bM_cO_x. Also, provided are a production method thereof, and a membrane-electrode assembly for fuel cells including the same. In the chemical formula 1, M, a, b, c, and x are the same as defined in the present specification.

Description

FIELD OF THE INVENTION The present invention relates to a catalyst for a fuel cell, a method for producing the same, and a membrane-electrode assembly for a fuel cell including the same. BACKGROUND ART [0002]

A method for producing the same, and a membrane-electrode assembly for a fuel cell including the same.

Representative examples of the fuel cell include a polymer electrolyte membrane fuel cell (PEMFC), a direct oxidation fuel cell, and the like. When methanol is used as the fuel in the direct oxidation fuel cell, it is referred to as a direct methanol fuel cell (DMFC).

Direct oxidation fuel cells have lower energy density than polymer electrolyte fuel cells, but are easier to handle and operate at lower temperatures, and can be operated at room temperature. In particular, they do not require a fuel reformer. The polymer electrolyte fuel cell has advantages of high energy density and high output.

In such a fuel cell, the stack for generating electricity may be a unit cell consisting of a membrane-electrode assembly (MEA) and a separator (also referred to as a bipolar plate) It has a stacked structure of several tens. The membrane-electrode assembly includes an anode electrode (also referred to as a "fuel electrode" or an "oxidizing electrode") and a cathode electrode (also referred to as a "cathode" or a "reducing electrode") sandwiching a polymer electrolyte membrane containing a proton- ) Are located in the vicinity of the surface of the substrate.

The principle of generating electricity in the fuel cell is that the fuel is supplied to the anode electrode as the fuel electrode and adsorbed to the catalyst of the anode electrode and the fuel is oxidized to generate hydrogen ions and electrons, Reaches the cathode electrode, and hydrogen ions pass through the polymer electrolyte membrane and are transferred to the cathode electrode. The oxidant is supplied to the cathode electrode, and the oxidant, the hydrogen ion and the electrons react with each other on the catalyst of the cathode electrode to generate electricity while generating water.

When such a fuel cell is used for an automobile, the gas composition of the anode electrode may be composed of oxygen and hydrogen at the time of start-up / shut-down or fuel starvation, Causing the voltage to increase by 1.6 V or more.

 If the voltage is changed to such a high voltage, the carbon used as the carrier of the fuel cell catalyst is corroded, and the corrosion of the carbon rapidly proceeds above 1V.

One embodiment is to provide a catalyst for a fuel cell which improves cell performance by preventing corrosion of the carrier and having high activity and stability.

Another embodiment is to provide a method for producing the catalyst for a fuel cell.

Another embodiment is to provide a membrane-electrode assembly for a fuel cell including the electrode for a fuel cell.

One embodiment provides a catalyst for a fuel cell comprising a reaction inducing material comprising an oxide represented by the following formula (1).

[Chemical Formula 1]

Ir _a Ru _b M _c O _x

(In the formula 1,

M is Fe, Co, Mn, Cu, Ni, Zn, Ti, V, Cr, Pd, Ag, Cd, In, Sn, Au, Os, W, Re, Rh,

the ratio of a / (b + c) is 0.3 to 3.5, the ratio of b / c is 0.5 to 25,

and x is an integer of 0.5 to 2.)

The oxide may comprise nanoparticles, nanorods, core-shells or combinations thereof.

The average particle diameter (D50) of the oxide may be 1 nm to 6 nm.

The reaction inducing material may further include a carrier for supporting the oxide, and the oxide may be included in an amount of 20% by weight to 99% by weight based on the total amount of the oxide and the carrier.

The reaction inducing material may further include SiO ₂ .

The reaction inducing material may further include a carrier for supporting the oxide and the SiO ₂ .

The oxide and the total content of SiO ₂ is the total amount of the oxide, the SiO ₂ and with respect to the total amount of the carrier may be included in 20% by weight to 99% by weight, it said SiO ₂ is the oxide, the SiO ₂ and the support By weight based on the total weight of the composition.

The carrier is graphite, Denka black, ketjen black, acetylene black, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nano ball, activated carbon, the stabilizing carbon, indium tin oxide _{(ITO), TiO 2, WO} , SiO 2 Or a combination thereof.

The catalyst for a fuel cell may further include an active material containing a metal, and the active material may further include a carrier for supporting the metal, wherein the metal is present in an amount of 10 wt% To 80% by weight.

The oxide may be included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the active material.

In another embodiment, there is provided a method comprising: mixing an iridium precursor, a ruthenium precursor, and a metal (M) precursor at an atomic ratio of: Subjecting the mixture to a first heat treatment; And subjecting the first heat-treated mixture to a second heat treatment to produce a reaction inducing material containing an oxide represented by the formula (1).

The step of obtaining the mixture may further include addition of SiO ₂ , and the step of removing at least a part of the SiO ₂ from the second heat-treated mixture after the second heat-treating step may be further included.

In the step of obtaining the mixture, a carrier may be further added.

The first heat treatment may be performed at a temperature of 150 ° C to 500 ° C under a hydrogen atmosphere, and the second heat treatment may be performed at a temperature of 250 ° C to 500 ° C under an air atmosphere.

Another embodiment includes a cathode electrode and an anode electrode positioned opposite to each other; And a polymer electrolyte membrane disposed between the cathode electrode and the anode electrode, wherein the cathode electrode and the anode electrode each comprise an electrode substrate and a catalyst layer disposed on the electrode substrate and including the catalyst, Electrode assembly.

The details of other embodiments are included in the detailed description below.

By preventing corrosion of the carrier and having high activity and stability, a fuel cell with improved performance can be realized.

1 is a schematic view showing a membrane-electrode assembly (MEA) for a fuel cell according to an embodiment.
2 is an exploded perspective view showing a stack of a fuel cell system according to one embodiment.
3 is a thermogravimetric analysis (TGA) graph for the catalyst layer of Example 4. FIG.
4 is a graph showing the voltage-current of the catalyst layers of Examples 1 to 4 and Comparative Examples 1 to 3.

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

It is to be understood that where a layer, film, region, plate, or the like is referred to as being "on" another portion, unless stated otherwise in this specification, .

The catalyst for a fuel cell according to an embodiment may use a reaction inducing material. Specifically, the reaction inducing material may include an oxide represented by the following formula (1).

[Chemical Formula 1]

Ir _a Ru _b M _c O _x

The oxide represented by Formula 1 has high water decomposition activity due to ruthenium (Ru) and high high voltage stability due to iridium (Ir) element, thereby improving durability against carrier corrosion.

In addition, the oxide can induce and accelerate a reaction for decomposing water at a high voltage to generate hydrogen and oxygen, for example, an oxygen evolution reaction (OER). According to this, when the start-stop of the automobile or fuel shortage, the voltage on the cathode side rises and carrier corrosion such as carbon occurs. If the oxygen generation reaction occurs a lot, water breakdown occurs instead of corrosion of the carrier at a high voltage, Can be mitigated or prevented.

In the formula 1, M may be Fe, Co, Mn, Cu, Ni, Zn, Ti, V, Cr, Pd, Ag, Cd, In, Sn, Au, Os, W, Re, Rh, . Oxides, which further contain metals of this kind in addition to Ru and Ir, are capable of decomposing water with ease due to their ability to bond with oxygen by increasing oxophilic properties. Accordingly, when the oxide is used as a catalyst for a fuel cell, higher activity can be obtained.

In the above formula (1), the ratio of a / (b + c) may be 0.3 to 3.5, and may be 1 to 3. The ratio of b / c may be 0.5 to 25, and may be 1 to 15 in detail. When an oxide having an atomic ratio of Ir, Ru, and M within the above range is used as a catalyst for a fuel cell, the cell performance can be improved with high activity and excellent stability.

In the above formula (1), x may be an integer of 0.5 to 2, and specifically may be 1 to 2. When x satisfies an integer within the above range, stable performance can be obtained without changing water decomposition activity at high voltage.

The oxide may comprise nanoparticles, nanorods, core-shells or combinations thereof. The oxide having the above shape may have a high dispersibility.

The average particle size (D50) of the oxide may be from 1 nm to 6 nm, and specifically from 2 nm to 5 nm. When the average particle diameter of the oxide is within the above range, the dispersibility is further improved and a high activity can be obtained by using a small amount of the oxide.

The reaction inducing material may further include a carrier for supporting the oxide.

The carrier is graphite, Denka black, ketjen black, acetylene black, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nano ball, activated carbon, the stabilizing carbon, indium tin oxide _{(ITO), TiO 2, WO} , SiO 2 Etc., or combinations thereof.

The stabilized carbon may be formed by heat-treating the Ketjen black at 1500 ° C to 3000 ° C, for example, 2000 ° C to 2800 ° C. The surface area of the stabilized carbon may be from 50 m ² / g to 700 m ² / g, for example from 70 m ² / g to 400 m ² / g.

The oxide may be included in an amount of 20 wt% to 99 wt%, for example, 20 wt% to 80 wt% and 30 wt% to 70 wt% based on the total amount of the oxide and the support. When the oxide is supported within the above content range, the dispersibility of the catalyst can be improved while ensuring high stability.

The reaction inducing material may further include SiO ₂ in addition to the oxide represented by the formula (1).

The SiO ₂ may be added at the time of synthesizing the reaction inducing material, and the added SiO ₂ may be removed by a post-treatment such as a base treatment, but a small amount may remain without being removed.

The SiO ₂ can serve as an initiator for initiating the oxygen generating reaction described above. That is, by starting the oxygen generating reaction at a lower voltage, the starting voltage can be further lowered. Therefore, when a small amount of SiO ₂ is added to the reaction inducing material, the oxygen generation reaction easily occurs even at a low voltage, so that corrosion of the carrier can be further prevented while ensuring high activity and stability.

The reaction inducing material may further include a carrier for supporting the oxide and the SiO ₂ . The description of the carrier is as described above.

The oxide and the total content of SiO ₂ may be contained at 20% by weight to 99% by weight with respect to the total of the oxides, the SiO ₂ and the support, for example, 20% to 80% by weight, 30% by weight To 70% by weight. When the total amount of the oxide and SiO ₂ is carried within the above range, the dispersibility of the catalyst can be improved while ensuring high stability.

The SiO ₂ may be included in an amount of 0.5 wt% to 7 wt%, for example, 1 wt% to 5 wt%, based on the total amount of the oxide, the SiO _2, and the carrier. When the SiO ₂ is included in the above content range, corrosion of the carrier can be further prevented while securing high activity and stability.

The reaction inducing material may be prepared by the following method.

The iridium precursor, the ruthenium precursor and the metal (M) precursor to an atomic ratio of the following formula 1 to obtain a mixture, subjecting the mixture to a first heat treatment, and then subjecting the first heat-treated mixture to a second heat treatment .

The iridium precursor may be, for example, hydrogen chloride iridium (H ₂ IrCl ₆ ), and the ruthenium precursor may include ruthenium chloride (RuCl ₃ ). The metal (M) precursor is a precursor of Fe, Co, Mn, Cu, Ni, Zn, Ti, V, Cr, Pd, Ag, Cd, In, Sn, Au, Os, Metal chlorides, metal nitrates, metal sulfonates and the like can be used.

At this time, the mixture can be obtained by further adding SiO ₂ . In this case, the process of removing at least part of the SiO ₂ from the second heat-treated mixture after the second heat treatment may be further performed.

The first heat treatment may be performed at a temperature of 150 ° C to 500 ° C under a hydrogen atmosphere, for example, at a temperature of 200 ° C to 400 ° C. Also, the second heat treatment may be performed at a temperature of 200 ° C to 500 ° C under an air atmosphere, specifically, at a temperature of 225 ° C to 300 ° C.

The removal of the SiO ₂ can be performed using a base such as NaOH, KOH, or HF acid.

The catalyst for a fuel cell according to one embodiment may use an active material in addition to the above-described reaction inducing material.

The active material may comprise a metal.

The metal may specifically include a platinum-based metal. The platinum-based metal may be at least one selected from the group consisting of platinum, ruthenium, osmium, platinum-M alloy (M is at least one element selected from the group consisting of Ga, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Mo, Os, and Pd), or a combination thereof. More specifically, the platinum-based metal is at least one selected from the group consisting of Pt, Pt-Ru alloy, Pt-W alloy, Pt-Ni alloy, Pt-Sn alloy, Pt-Mo alloy, Pt- A Pt-Co-Ni alloy, a Pt-Co-Fe alloy, a Pt-Co-S alloy, a Pt-Fe-S alloy, a Pt- A Fe-Ir alloy, a Pt-Co-Ir alloy, a Pt-Cr-Ir alloy, a Pt-Ni-Ir alloy, a Pt-Au-Co alloy, a Pt- Pt-Ru-W alloy, Pt-Ru-Mo alloy, Pt-Ru-V alloy, Pt-Ru-Rh-Ni alloy, Pt-Ru-Sn-W alloy or a combination thereof can be used .

The active material may further include a carrier for supporting the metal. In other words, the metal may be used alone as the active material, or may be used in a form supported on the carrier

The carrier is graphite, Denka black, ketjen black, acetylene black, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nano ball, activated carbon, the stabilizing carbon, indium tin oxide _{(ITO), TiO 2, WO} , SiO 2 Or a combination thereof.

When the metal is used in the form of being supported on the support, the metal may be included in an amount of 10 to 80% by weight, and more specifically 20 to 65% by weight, based on the total amount of the metal and the support . When the metal is supported within the above-mentioned content range, a highly active fuel cell can be secured and the production of the catalyst layer becomes easy.

The oxide represented by Formula 1 of the reaction inducing material may be contained in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the active material, specifically, the metal and the carrier. For example, 7.5 parts by weight. When the oxide of the reaction inducing material is included in the above content range, a catalyst for fuel cell having excellent stability at high voltage can be secured through a high water decomposition activity, and the performance of existing membrane-electrode assemblies is also prevented even with a small amount of noble metal And can have high activity.

According to another embodiment, there is provided an electrode for a fuel cell comprising the above-mentioned catalyst.

Specifically, the electrode for a fuel cell includes an electrode substrate and a catalyst layer formed on the electrode substrate.

The catalyst layer includes the above-described catalyst, and may further include an ionomer for improving adhesion of the catalyst layer and transferring hydrogen ions.

The ionomer may be a polymer resin having hydrogen ion conductivity, specifically, a polymer resin having at least one cation-exchange group selected from a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, Can be used. More specifically, examples of the polymer include fluorine polymer, benzimidazole polymer, polyimide polymer, polyetherimide polymer, polyphenylene sulfide polymer, polysulfone polymer, polyether sulfone polymer, polyether ketone polymer, poly Ether-ether ketone-based polymer, and polyphenylquinoxaline-based polymer may be used. More specifically, poly (perfluorosulfonic acid), poly (perfluorocarboxylic acid), copolymer of tetrafluoroethylene and fluorovinyl ether containing sulfonic acid group, sulfated polyether ketone, aryl ketone, poly 2,2'-m-phenylene) -5,5'-bibenzimidazole] and poly (2,5-benzimidazole [ ) May be used.

In the polymer resin having hydrogen ion conductivity, H may be substituted with Na, K, Li, Cs or tetrabutylammonium in the cation exchanger at the side chain terminal. In the case of replacing H with Na in the ion exchange group at the side chain terminal, NaOH is substituted in the preparation of the catalyst composition and tetrabutylammonium hydroxide is used in the case of replacing with tetrabutylammonium, and K, Li or Cs is also substituted with a suitable compound . ≪ / RTI > Since this substitution method is well known in the art, a detailed description thereof will be omitted in this specification.

The ionomer may be used singly or in the form of a mixture, and may optionally be used together with a nonconductive compound for the purpose of further improving the adhesion with the polymer electrolyte membrane. The amount of the nonconductive compound to be used is preferably adjusted to suit the intended use.

Examples of the nonconductive compound include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene / tetrafluoro (PVdF-HFP), dodecyltrimethoxysilane (DMSO), ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer At least one selected from silbenzenesulfonic acid and sorbitol can be used.

The ionomer may be contained in an amount of 15% by weight to 50% by weight based on the total amount of the catalyst layer, and specifically 20% by weight to 40% by weight. When the ionomer is contained within the above range, the adhesion of the catalyst layer is improved and the hydrogen ion transfer efficiency is increased.

The electrode substrate plays a role of supporting the electrode and diffusing the fuel and the oxidant into the catalyst layer to facilitate the access of the fuel and the oxidant to the catalyst layer.

The electrode substrate may be formed of a conductive substrate, and specifically, a porous film or polymer fiber composed of a carbon paper, a carbon cloth, a carbon felt, or a metal cloth A metal film is formed on the surface of the cloth formed with the metal film), but the present invention is not limited thereto.

The electrode substrate may be water repellent with a fluorine-based resin. In this case, it is possible to prevent the reactant diffusion efficiency from being lowered due to water generated when the fuel cell is driven.

Examples of the fluorine-based resin include polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polyperfluoroalkyl vinyl ether, polyperfluorosulfonyl fluoride, alkoxyvinyl ether, fluorinated ethylene propylene (fluorinated ethylene propylene), polychlorotrifluoroethylene, or copolymers thereof.

In addition to the electrode substrate and the catalyst layer, the electrode for a fuel cell may further include a microporous layer for enhancing a reactant diffusion effect in the electrode substrate.

The microporous layer is generally made of a conductive powder having a small particle diameter such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotube, carbon nanowire, nano-horn or a carbon nano ring.

According to another embodiment, there is provided a membrane-electrode assembly for a fuel cell including the electrode for a fuel cell.

The membrane-electrode assembly for a fuel cell will be described with reference to FIG.

1 is a schematic view showing a membrane-electrode assembly (MEA) for a fuel cell according to an embodiment.

1, the fuel cell membrane-electrode assembly 20 includes a polymer electrolyte membrane 25 and a cathode electrode 21 and an anode electrode 22 located on both sides of the polymer electrolyte membrane 25 do.

At least one of the cathode electrode 21 and the anode electrode 22 uses the above-described electrode for a fuel cell.

The polymer electrolyte membrane 25 is a solid polymer electrolyte having a thickness of 10 m to 200 m and has a function of ion exchange for moving hydrogen ions generated in the catalyst layer of the anode electrode to the catalyst layer of the cathode electrode.

The polymer electrolyte membrane 25 is generally used as a polymer electrolyte membrane in a fuel cell, and any polymer electrolyte membrane having hydrogen ion conductivity may be used. Specific examples include a polymer resin having at least one cation-exchange group selected from a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group and derivatives thereof in the side chain.

Specific examples of the polymer resin include fluorine-based polymers, benzimidazole-based polymers, polyimide-based polymers, polyetherimide-based polymers, polyphenylene sulfide-based polymers, polysulfone-based polymers, polyether sulfone- (Perfluorosulfonic acid) (commercially available from Nafion), poly (perfluoro (meth) acrylate, perfluoro (meth) acrylate and the like), poly Carboxylic acid), a copolymer of tetrafluoroethylene and fluorovinyl ether containing a sulfonic acid group, a dehydrofluorinated sulfated polyether ketone, an aryl ketone, poly [(2,2'-m-phenylene) -5,5 '-Bibenzimidazole] [poly (2,2' - (m-phenylene) -5,5'-bibenzimidazole] and poly (2,5-benzimidazole).

The fuel cell includes a stack in which supplied hydrogen gas electrochemically reacts with an oxidant to generate electrical energy. The stack will be described with reference to FIG.

2 is an exploded perspective view illustrating a stack of fuel cells according to one embodiment.

Referring to FIG. 2, the stack 130 includes a plurality of unit cells 131 for generating electrical energy by inducing an oxidation / reduction reaction of supplied hydrogen gas and an oxidizing agent to be supplied.

Each unit cell 131 refers to a unit cell that generates electricity. The unit cell 131 includes a membrane-electrode assembly 132 for oxidizing / reducing hydrogen gas and oxygen in the oxidizer, a hydrogen- (Also referred to as a bipolar plate) 133 for supplying the bipolar plate 132 to the bipolar plate 132. The membrane-electrode assembly 132 is as described above. The separator 133 is disposed on both sides of the membrane-electrode assembly 132 with the center thereof as the center. At this time, the separator located at the outermost side of the stack may be referred to as an end plate.

The end plate of the separator 133 is provided with a pipe-shaped first supply pipe 133a1 for injecting hydrogen gas to be supplied and a pipe-shaped second supply pipe 133a2 for injecting oxygen gas, The end plate is provided with a first discharge pipe 133a3 for discharging hydrogen gas remaining unreacted in the plurality of unit cells 131 to the outside and a second discharge pipe 133b1 for discharging the remaining unreacted oxidant from the unit cell 131 to the outside And a second discharge pipe 133a4 for discharging the gas to the outside.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the examples.

(For fuel cells) The catalyst layer  Composition Preparation)

Example  One

A first catalyst (Tanaka TEC36F52) carrying 52 wt% of a Pt ₃ Co alloy on 48 wt% of carbon was prepared.

A mixture obtained by mixing iridium chloride (H ₂ IrCl ₆ ), ruthenium chloride (RuCl ₃ ) and iron nitrate (Fe (NO ₃ ) ₃ .9H ₂ O) so that the atomic ratio of Ir, Ru and Fe is 8: 2: After the first heat treatment at a temperature of 300 캜 in a hydrogen atmosphere, the second heat treatment was performed at a temperature of 250 캜 in an air atmosphere to prepare a second catalyst of Ir ₈ Ru ₂ FeO _x (0.5 ≤ _x ≤ 2).

A catalyst layer composition was prepared by mixing 67% by weight of a catalyst obtained by mixing 92.6% by weight of the first catalyst and 7.4% by weight of the second catalyst with 33% by weight of Nafion (DuPont). At this time, Ir ₈ Ru ₂ FeO _x (0.5? _{X? 2} ) was contained in an amount of 8 parts by weight based on 100 parts by weight of the first catalyst.

Example  2

A mixture 80 of iridium chloride (H ₂ IrCl ₆ ), ruthenium chloride (RuCl ₃ ) and iron nitrate (Fe (NO ₃ ) ₃ .9H ₂ O) so that the atomic ratio of Ir, Ru and Fe is 8: 2: The catalyst layer composition was prepared in the same manner as in Example 1, except that the weight% was carried on 20 wt% of stabilized carbon formed by heat-treating Ketjenblack at 2250 DEG C and then subjected to a first heat treatment.

Example  3

A mixture _{20 of} iridium chloride (H ₂ IrCl ₆ ), ruthenium chloride (RuCl ₃ ) and iron nitrate (Fe (NO ₃ ) ₃ .9H ₂ O) so that the atomic ratio of Ir, Ru and Fe was 8: 2: After 80% by weight of SiO ₂ was added to the mixture, the mixture was subjected to a first heat treatment, followed by a secondary heat treatment at a temperature of 250 ° C in an air atmosphere. Then, SiO ₂ was partially removed through NaOH to obtain Ir ₈ Ru ₂ FeO _x ≤2) to prepare a second catalyst consisting of 94 wt.% SiO ₂ and 6% by weight.

Using the second catalyst, a catalyst layer composition was prepared in the same manner as in Example 1.

Example  4

A mixture _{20 of} iridium chloride (H ₂ IrCl ₆ ), ruthenium chloride (RuCl ₃ ) and iron nitrate (Fe (NO ₃ ) ₃ .9H ₂ O) so that the atomic ratio of Ir, Ru and Fe was 8: 2: 75% by weight of SiO ₂ was added to the solution, and Ketjenblack was supported on 5% by weight of stabilized carbon formed by heat treatment at 2250 ° C, followed by a first heat treatment, a second heat treatment at 250 ° C in an air atmosphere, SiO ₂ was partially removed to prepare a second catalyst in which 76 wt% of Ir ₈ Ru ₂ FeO _x (0.5? _{X? 2} ) and 4 wt% of SiO ₂ were supported on 20 wt% of stabilized carbon.

Using the second catalyst, a catalyst layer composition was prepared in the same manner as in Example 1.

Comparative Example  One

A catalyst layer composition was prepared in the same manner as in Example 1 except that the second catalyst was not used in Example 1.

Comparative Example  2

The mixture obtained by mixing iridium chloride (H ₂ IrCl ₆ ) and ruthenium chloride (RuCl ₃ ) so as to have an Ir and Ru atomic ratio of 8: 3 was subjected to a first heat treatment at 300 ° C. in a hydrogen atmosphere, To prepare a second catalyst of Ir ₈ Ru ₃ O _x (0.5? _X ? 2).

A catalyst layer composition was prepared in the same manner as in Example 1 except that the second catalyst prepared above was used instead of the second catalyst in Example 1.

Comparative Example  3

80 wt% of a mixture obtained by mixing iridium chloride (H ₂ IrCl ₆ ) and ruthenium chloride (RuCl ₃ ) so that the atomic ratio of Ir and Ru was 8: 3 was loaded on 20 wt% of stabilized carbon formed by heat- Thereafter, the first catalyst was subjected to a first heat treatment at a temperature of 300 ° C. in a hydrogen atmosphere, followed by a second heat treatment at a temperature of 250 ° C. in an air atmosphere to prepare a second catalyst of Ir ₈ Ru ₃ O _x (0.5 ≦ _x ≦ 2).

A catalyst layer composition was prepared in the same manner as in Example 2 except that the second catalyst prepared above was used instead of the second catalyst in Example 2.

(Preparation of membrane-electrode assembly for fuel cell)

The catalyst layer compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were coated on a fluorinated ethylene propylene (FEP) film and sufficiently dried in a convection oven at a temperature of 90 ° C for 5 hours to prepare a catalyst layer The catalyst layer was used as a cathode catalyst layer constituting the cathode electrode and an anode catalyst layer constituting the anode electrode.

The cathode catalyst layer and the anode catalyst layer were transferred to a fluorine-based membrane, and the FEP film was removed to prepare a membrane-catalyst layer assembly. A membrane-electrode assembly was prepared using the prepared membrane-catalyst layer junction body and SGL 35BC diffusion layer.

Rating 1

20 mg of the second catalyst prepared in Example 4 was placed in a thermogravimetric analyzer, and thermogravimetric analysis (TGA) was carried out by heating to 800 ° C. at a rate of 10 ° C./min in an air atmosphere to measure the weight loss. The results are shown in Fig.

3 is a thermogravimetric analysis (TGA) graph for the catalyst layer of Example 4. FIG.

Referring to FIG. 3, it can be seen that the amount of the catalyst decreases in the vicinity of about 165 ° C. in the case of Example 4. This is due to the effect of FeOx, and thus it can be confirmed that the oxide used as the reaction inducing material according to one embodiment contains an additional metal such as Fe in addition to Ir and Ru.

Rating 2

In order to evaluate the oxygen generating reaction (OER) activity of the catalyst layers prepared in Examples 1 to 4 and Comparative Examples 1 to 3, the temperature of the unit cell was maintained at 65 ° C, and N ₂ was supplied to the cathode electrode at a relative humidity of 100% And H ₂ of 100% relative humidity was supplied to the anode electrode, and a cyclic voltammetry (CV) was performed. The voltage scan range extends from 0V to 1.5V to the region where water degradation occurs. The results are shown in Fig.

4 is a graph showing the voltage-current of the catalyst layers of Examples 1 to 4 and Comparative Examples 1 to 3.

Referring to FIG. 4, it can be seen that the current increases sharply below 1.2 V in Examples 1 to 4. Therefore, when the reaction inducing material according to one embodiment is used as a catalyst for a fuel cell, the water is first decomposed rather than the corrosion of the carbon, so that the stability of the fuel cell catalyst Can be increased.

20: Membrane-electrode assembly for fuel cell
21: cathode electrode
22: anode electrode
25: Polymer electrolyte membrane
130: stack
131: Unit cell
132: membrane-electrode assembly
133: Separator

Claims (20)

A reaction inducing material comprising an oxide represented by the following formula (1)
And a catalyst for fuel cells.
[Chemical Formula 1]
Ir _a Ru _b M _c O _x
(In the formula 1,
M is Fe, Co, Mn, Cu, Ni, Zn, Ti, V, Cr, Pd, Ag, Cd, In, Sn, Au, Os, W, Re, Rh,
the ratio of a / (b + c) is 0.3 to 3.5, the ratio of b / c is 0.5 to 25,
and x is an integer of 0.5 to 2.) The method according to claim 1,
Wherein the oxide comprises nanoparticles, nanorods, core-shells or combinations thereof. The method according to claim 1,
Wherein the average particle diameter (D50) of the oxide is 1 nm to 6 nm. The method according to claim 1,
Wherein the reaction inducing material further comprises a carrier for supporting the oxide. 5. The method of claim 4,
Wherein the oxide is contained in an amount of 20 wt% to 99 wt% based on the total amount of the oxide and the support. The method according to claim 1,
The reaction-inducing substance is a catalyst for a fuel cell further comprising an SiO _2. The method according to claim 6,
Wherein the reaction inducing material further comprises a carrier for supporting the oxide and the SiO ₂ . 8. The method of claim 7,
The oxide and the total content of SiO ₂ is a fuel cell catalyst which comprises 20% to 99% by weight relative to the total amount of the oxides, the SiO ₂ and the support. 8. The method of claim 7,
Wherein the SiO ₂ is contained in an amount of 0.5 wt% to 7 wt% based on the total amount of the oxide, the SiO _2, and the support. 8. The method according to claim 4 or 7,
The carrier is graphite, Denka black, ketjen black, acetylene black, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nano ball, activated carbon, the stabilizing carbon, indium tin oxide _{(ITO), TiO 2, WO} , SiO 2 Or a combination thereof. 7. The method according to claim 1 or 6,
Active substance comprising metal
Wherein the catalyst is a catalyst for fuel cells. 12. The method of claim 11,
Wherein the active material further comprises a carrier for supporting the metal. 13. The method of claim 12,
Wherein the metal is contained in an amount of 10% by weight to 80% by weight based on the total amount of the metal and the support. 13. The method of claim 12,
Wherein the oxide is contained in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the active material. Mixing an iridium precursor, a ruthenium precursor, and a metal (M) precursor to an atomic ratio of the following formula 1 to obtain a mixture;
Subjecting the mixture to a first heat treatment; And
Subjecting the first heat-treated mixture to a second heat treatment to produce a reaction inducing material containing an oxide represented by the following formula (1)
And a catalyst layer formed on the catalyst layer.
[Chemical Formula 1]
Ir _a Ru _b M _c O _x
(In the formula 1,
M is Fe, Co, Mn, Cu, Ni, Zn, Ti, V, Cr, Pd, Ag, Cd, In, Sn, Au, Os, W, Re, Rh,
the ratio of a / (b + c) is 0.3 to 3.5, the ratio of b / c is 0.5 to 25,
and x is an integer of 0.5 to 2.) 16. The method of claim 15,
The step of obtaining the mixture further comprises adding SiO ₂ ,
The second and subsequent steps of heat treatment from the second heat-treated mixture and further comprising removing at least a portion of the SiO ₂
A method for producing a catalyst for a fuel cell. 16. The method of claim 15,
Wherein the step of obtaining the mixture further comprises adding a carrier. 16. The method of claim 15,
Wherein the first heat treatment is carried out at a temperature of 150 ° C to 500 ° C under a hydrogen atmosphere. 16. The method of claim 15,
Wherein the second heat treatment is performed at a temperature of 250 ° C to 500 ° C under an air atmosphere. A cathode electrode and an anode electrode facing each other; And
And a polymer electrolyte membrane disposed between the cathode electrode and the anode electrode,
The cathode electrode and the anode electrode
Electrode substrate, and
A catalyst layer disposed on the electrode substrate and comprising the catalyst of claim 1;
Membrane-electrode assemblies for fuel cells.

Images